The present invention relates generally to group controls for elevators and, in particular, to an apparatus for the immediate allocation of target calls in dependence on the location of the call entry device on a floor.
Elevator group controls are known which have call registering and indicating devices located on the floors served by the elevator cars and include a keyboard for the entry of calls for desired target floors. Floor call memories, which are associated with the elevators of the 15 group and connected with the call registering and indicating devices respond to the entry of a call at a floor by storing a call identifying the entry floor and a call identifying the target floor Load memories are also provided in which the number of the persons present in the respective elevator car is stored for each floor. Travelling time memories and car position registers are associated with the elevator cars of the group for storing the travel time between the floors and the current position of the car respectively.
A group control, which is similar to the present invention and which uses the least waiting time of all passengers as the criterion for the allocation of the cars to the entered calls, is shown in the European Patent Application No. EP-A 0 356 731. In this control, the travel targets can be entered at the floors, for example, through the use of the call registering and indicating devices shown in the European Patent Application No. EP-A 0 320 583. Immediately after the registration and transmission of a call into a floor call memory divided according to entry and target floors, a computer in the form of a microprocessor ascertains a sum for each car from data specific to that elevator car, which sum is called operating costs and corresponds to the waiting time which would occur for the passengers should the call be served. The operating costs are transferred immediately after the computation into a costs register and then compared immediately with the operating costs of the other elevators by means of a comparison device. In this case an allocation instruction is stored in an allocation memory of that elevator which displays the least operating costs. Immediately after the allocation of a car to the call, the elevator concerned and its position are indicated in an indicating field of the actuated call registering and indicating device so that the passenger can move to the associated shaft door in time before the elevator car arrives.
Optimum results in respect of the lowest waiting times of the passengers can be achieved by the aforedescribed group control. In larger installations with several elevators however, it must be recognized that a passenger needs more or less time for travelling the path to the shaft door of the allocated elevator according to the relative position of the actuated call registering and indicating device on the floor. For this reason, after arrival at the floor, the door of the elevator must be kept open sufficiently long so that the passenger positioned the longest distance away can still board. In the case of a car arriving early, there results not only a loss of time for the persons situated in the car, but also for the entire elevator control system so that the operating quality and quantity is impaired.
The present invention is based on the task of improving the above described elevator group control in such a manner that cars in which a loss of time would arise through doors being kept open for too long a time are excluded from the call allocation.